Review Article
Myocardial blood flows and reserves on solid state camera: Correlations with coronary history and cardiovascular risk factors

https://doi.org/10.1007/s12350-021-02659-xGet rights and content

Abstract

Objectives

Study designed to test association between stress-induced myocardial blood flow (sMBF), resting MBF (rMBF), and MBF reserve (MFR) and coronary artery disease (CAD) in a population of CAD and non-coronary patients. Secondary objectives were to confront visual analysis and dynamic analysis and to explore potential association between MBF and several cardiovascular risk factors

Methods

A total of 155 patients who underwent dynamic myocardial perfusion imaging on a CZT camera were included. sMBF, rMBF, and MFR were evaluated, and cardiovascular risk was assessed.

Results

Significantly lower total sMBF and MFR were observed in CAD patient vs non-CAD patient. In comparison with visual analysis, lower sMBF were found in pathologic territory, lower rMBF in necrotic territory and lower MFR in necrotic ones. A significant correlation between total sMBF, rMBF and diabetes was found.

Conclusion

sMBF and MFR as assessed on CZT gamma-cameras can be used to determine the coronary state. Low total sMBF might be an independent risk factor of coronaropathy. An inverse correlation was suggested between total sMBF and rMBF with diabetes.

Introduction

A semi-quantitative evaluation of regional myocardial perfusion is the standard practice in nuclear cardiology. This type of evaluation has proven to be a reproducible and accurate method to detect flow-limiting stenosis and has been a recommended practice since the 2019 European guidelines reaffirmed the use of noninvasive functional imaging modalities or coronary tomography angiography (CTA) as a screening test for coronary artery disease (CAD) in patients with clinical symptoms (grade I). These guidelines recommend the use of functional imaging in cases of doubtful or infradiagnostic CTA.1

However, there is growing interest in the scientific community to quantitatively evaluate myocardial blood flow (MBF) in cases of suspected or proven coronary CAD. Until recently, this was possible only through invasive coronary angiography (ICA), but many imaging modalities, such as positron emission tomography/computed tomography (PET/CT), magnetic resonance imaging, CT, and echography, have adapted noninvasive measurements. According to a major pool analysis,2 PET myocardial analyses (using 82Rb and 13N-ammonia) have a sensitivity of 91%, specificity of 86%, positive predictive value of 81%, and negative predictive value of 93% for detecting ischemia.3

The recent development of solid-state dedicated cardiac single photon emission computed tomography (SPECT) camera allowed stress-induced MBF (sMBF), resting MBF (rMBF), and myocardial flow reserve (MFR), defined as the ratio of sMBF and rMBF, to be quantified. Many studies have refined modalities and improved the performance of this nuclear imaging modality resulting in a robust and reproducible method for quantitative analyses.4, 5, 6,7

However, the interpretation of quantitative results in this modality is complex and may be subject to variation due to several factors, such as clinical context, modality, and the characteristics of the acquisition (camera, image reconstruction procedure), blood pressure, heart rate of the patient at the time of acquisition,8 and other cardiovascular risk factors that may also be involved with an underlying microvascular myocardial injury.

In this exploratory study, we analyzed several dynamic acquisition results among a population of patients referred to the Haut Lévêque Hospital (CHU de Bordeaux) who underwent dynamic myocardial perfusion imaging (MPI) to build a usable dataset of MBF and myocardial blood reserve in a large population of coronary and non-coronary patients and to test the correlation between several cardiovascular risk factors using a solid-state dedicated cardiac camera.

This exploratory study aimed at testing association between sMBF, rMBF and MFR and CAD in a large population of coronary and non-coronary patients using a solid-state dedicated cardiac camera. Secondary objectives were to confront visual analysis and quantitative analysis and to explore potential association between sMBF, rMBF, MFR and several cardiovascular risk factors

Section snippets

Patients

We designed a retrospective analysis of 150 patients (75 with known CAD and 75 without CAD). We randomly screened them among all patients referred to the CHU of Bordeaux (Haut Lévêque Hospital) from December 2018 to June 2020 for a dynamic MPI with an evaluation of MBF and MFR. Coronary patients had to present a recent positive ICA defined as at least one >50% stenosis in at least one coronary territory. Non-coronary patients must present a clear medical history without any known history of a

Results

Among 793 patients who underwent myocardial scintigraphy during the defined period, we randomly screened 393 patients for an inclusion of 80 patients with known CAD and 75 patients without CAD and negative scintigraphy who matched the inclusion criteria. The patient characteristics are summarized in Table 1. In total, 112 patients had negative scintigraphy (all 75 non-CAD patients and 37 CAD patients) and 43 a positive one with at least one lesion. Among those, 20 presented an ischemic lesion

Discussion

Our study is, to our knowledge, the first to analyze MBF values in a large population of coronary and non-coronary patients and study the impact of cardiovascular risks factors on MBF values recorded on SPECT-CZT.

New Knowledge Gained

sMBF and MFR assessed using a cardiac CZT camera were inversely correlated with the coronary states of patients. sMBF was used to identify an ischemic or necrotic dysfunction in a specific territory. Low MFR was used to differentiate ischemic lesions from necrotic ones. An inverse correlation was observed between total sMBF and diabetes. Inverse correlations were observed between total MFR and age and male sex.

Conclusion

This exploratory study is concordant with previous recently published results25, 26, 27, 28,29 regarding quantitative assessment of myocardial blood flows and reserves using CZT gamma-cameras. It reinforces the utility of this measurement to differentiate coronary and non-coronary patients in global analyses and by territory. The correlations found between several cardiovascular risks factors with flows and reserves values will require further investigations.

Author contribution

The manuscript has been seen and approved by all authors and each author has contributed significantly to the submitted work.

Disclosure

There are no conflict of interest and no source of funding.

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